Absorbent articles for personal hygiene, such as disposable diapers for infants, training pants for toddlers or adult incontinence undergarments are designed to absorb and contain body exudates, in particular large quantity of urine. These absorbent articles comprise several layers providing different functions, for example a topsheet, a backsheet and in-between an absorbent core, among other layers.
The function of the absorbent core is to absorb and retain the exudates for a prolonged amount of time, for example overnight for a diaper, minimize re-wet to keep the wearer dry and avoid soiling of clothes or bed sheets. The majority of currently marketed absorbent articles comprise as absorbent material a blend of comminuted wood pulp with superabsorbent polymers (SAP) in particulate form, also called absorbent gelling materials (AGM), see for example U.S. Pat. No. 5,151,092 (Buell). Absorbent articles having a core consisting essentially of SAP as absorbent material (so called “airfelt-free” cores) have also been proposed but are less common than traditional mixed cores (see e.g. WO2008/155699 (Hundorf), WO95/11652 (Tanzer), WO2012/052172 (Van Malderen)).
Absorbent articles comprising an absorbent core with slits or grooves have also been proposed, typically to increase the fluid acquisition properties of the core. WO95/11652 (Tanzer) discloses absorbent articles which include superabsorbent material located in discrete pockets having water-sensitive and water-insensitive containment structure. WO2009/047596 (Wright) discloses an absorbent article with a slit absorbent core.
It is known to provide a sub-layer, typically a non-woven, between the topsheet and the absorbent core. These sub-layers are designed to quickly acquire and/or distribute the fluid away from the topsheet and into the core. These sub-layers are sometimes called “wicking layer”, “surge layer”, “acquisition layer” or “distribution layer”. Articles having only one of these sub-layers are known. Articles having two sub-layers or more, in particular as a first sub-layer may have a high capillarity which pulls the fluid quickly away from the topsheet and a second sub-layer a larger void area to distribute the fluid over a large surface over the core, are also known. These sub-layers typically do not comprise superabsorbent articles material. In the following, the term “acquisition-distribution system” (“ADS”) will be used to designate the layer or combination of discrete layers (one, two, or more) present between the topsheet and the backsheet and providing these acquisition and/or distribution function, irrespective of the number of layers.
Acquisition-distribution systems comprising a single layer are disclosed for example in WO94/23761 (Payne), which discloses an acquisition layer comprising an homogeneous composition of hydrophilic fibrous material and a storage layer comprising a mixture of hydrophilic fibrous material and discrete particles of absorbent gelling material. The acquisition layer has an acquisition zone towards the front of the article of relatively lower average density and relatively lower average basis weight than a distribution zone towards the back of the article. Another example of ADS having a single layer can be found in U.S. Pat. Nos. 5,486,166 and 5,490,846 (Bishop).
US2008/0312621 and US2008/0312622 (Hundorf) describe a disposable absorbent article comprising a chassis including a topsheet and a backsheet, a substantially cellulose free absorbent core located between the topsheet and the backsheet and having a wearer facing side oriented toward a wearer when the article is being worn and an opposed garment facing side, and a “liquid acquisition system” comprising chemically cross-linked cellulosic fibers disposed between the liquid permeable topsheet and the wearer facing side of the absorbent core. The liquid acquisition system may also comprise an upper acquisition layer made of a latex bonded nonwoven.
US2004/220541 (Suzuki) discloses an absorbent sheet having concave and convex portions on its surface and spontaneously exhibiting a three-dimensional structure in that a concave-convex structure is formed. US2007/244455 (Hansson) discloses an absorbent core in an absorbent article provided with at least two folding guides extending in a substantially longitudinal direction in the crotch region and dividing at least a part of the crotch region of the absorbent core in a central portion and two lateral portions as seen in a transverse direction. At least two stretchable crotch elastic members are arranged in the crotch portion of the article and are attached to the absorbent core and/or to the inner or outer cover.
Absorbent products which are flexible in the crotch region provide the benefits of improved freedom of movement for the wearer, especially when the user's legs compress the crotch region of the article laterally. However the inventors have found that highly flexible products may in generally have a poor resiliency when becoming wet, and thus tend to lose their shape when compressed by the movement of the wearer's legs. As the absorbent core is deformed, the product can fail performing properly and this increases the chance of failure such as fluid leakages.
Acquisition or distribution layers having a relatively high amount of synthetic fibers can provide additional resiliency to the article if their basis weight is high enough. However, these layers may have the disadvantages of causing high rewet due to poorer fluid handling properties of the synthetic fibers. There is a need for absorbent articles having high crotch resiliency, while at the same time providing high flexibility and good fluid handling properties.